A disconnecting means was installed for an ESS to disconnect it from all wiring systems it is connected to. The disconnecting means was installed within sight from the ESS. The disconnect is not permitted to be installed ___ feet away from the ESS.

• A. 5
• B. 10
• C. disconnect installed within the ESS
• D. 50

Answer: (D)

The key idea is that an energy storage system must have a disconnecting means that is readily accessible, within sight of the ESS, and not more than fifty feet away from it. Being within sight allows an operator to verify the ESS is isolated when the disconnect is operated, improving safety during de-energization. Since the disconnect is already within sight, the distance limit becomes the enforcing constraint: it cannot be installed farther than fifty feet from the ESS. So the maximum allowed distance is fifty feet; placing it beyond that would violate the requirement. Distances such as five or ten feet would also be acceptable under the rule, but the prompt asks for the distance that cannot be exceeded, which is fifty feet. Installing the disconnect inside the ESS would not provide the required separate disconnecting means.